Pyrotechnic composition



1955 R. H. HEISKELL PYROTECHNIC COMPOSITION Filed June 9, 1955 FIGJ.

BURNING RATES OF BARIUM PEROXIDE AND CHROMIUM SULFIDE MIXTURES 7 l4 BURNING TIME(SEGONDS)0OLUMN I"LONG x 3/8"DIA.

O O o 5 FIG.2.

INVENTOR R. H. HEISKELL United States Patent 2,726,944 PYROTECHNIC COlViPOSITION Raymond H. Heiskell, San Bruno, Calif.

Application June 9, 1955, Serial No. 514,407

4 Claims. (Cl. 52-2) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to an igniter mixture and more particularly it concerns a dark burning non-flash igniter composition adapted to ignite the tracer composition arranged within a projectile.

Heretofore tracer ammunition used by our armed forces proved unsatisfactory especially when used in night encounters in that, under conditions of darkness, the ignition of the igniter composition which ignites the main tracer charge produced a blinding flash and too much light streak at the muzzle of the gun, thus illuminating and disclosing the position of the gun to the enemy and confusing and misleading the gunner or fire director when aiming of the gun was accomplished by observation of the tracer streak.

Various attempts have been made to produce an igniter for a tracer composition which burns without a visible flame. These prior art compositions were sufiiciently luminous to cause the trajectory of the projectile to be visible, especially at night, lacked stability under adverse temperature and humidity conditions, and generally proved unsatisfactory as the burning rate thereof was too rapid for the purpose intended and the ignition sensitivity characteristic not uniform.

The compositions of the present invention, which are disclosed in Serial Numbers 130,582, 130,583, and 130,586 filed December 1, 1949, by the present inventor, all abandoned, this application being a continuation in part thereof, are adapted to eliminate the above mentioned disadvantages of the prior art compositions.

Accordingly, it is an object of the present invention to provide dark burning non-flash igniter compositions which may serve to ignite the tracer mixture of a projectile.

It is a further object of the invention to provide a delayed ignition projectile tracer comprising a dark burning non-flash ignition pellet for igniting the projectile tracer wherein the ignition pellet comprises a composition of the invention.

It is still a further object of the invention to provide dark burning non-flash igniter compositions having desirable burning rates, uniform ignition sensitivity characteristics, and that are stable under adverse temperature and humidity conditions.

Still other objects and the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description and the drawing, wherein:

Fig. 1 of the drawing graphically illustrates the burning rate of compositions of the invention and more particularly the burning rate of barium peroxide and chromium sulfide mixtures; and

Fig. 2 is a sectional view of a projectile, with a portion thereof cut away, illustrating the novel dark burning non-flash delayed ignition tracer of the invention.

2,726,944 Patented Dee 13, 1955 In an igniter composition of the type herein disclosed there are three characteristics which are essential to its proper functioning. These characteristics are:

1. Burning without visible flame and with a flame hot enough to ignite the tracer composition;

, 2. Burning at the proper rate of speed to give the required time delay between the firing of the projectile and the ignition of the tracer composition; and

3. Stability under adverse conditions to thereby assure that the igniter will function under any condition of humidity or temperature which may be encountered in combat areas.

The composition of the present invention having the foregoing characteristics comprises a mixture of barium peroxide as the oxidizing agent, and a sulfide selected from the group consisting of chromium monosulfide, chromium tetrasulfide, and selenium sulfide. A small quantity of a hinder or lubricant is preferably added to the mixture, the lubricant being one adapted to make the loading operation easier and to eliminate the possibility of ignition during loading, and the binder being employed to permit the formation of the powder into pellet form. Graphite is an excellent lubricant while some substances such, for example, as stearic acid perform the function of both lubricant and binder.

The ingredients of the composition described above may be varied within the following limits:

From an inspection of the graph shown as Fig. 1 in the drawing, it will be apparent that a composition of desired burning speed may be selected by varying the percentage composition of the ingredients. Thus the preferred composition for use as a dark igniter for a high velocity projectile such as the 20 mm. type will be characterized by a minimum burning time and have relatively high percentages of barium peroxide. Obviously other mixtures having slower burning speeds may be used and in some instances such mixtures may be desirable when a longer time delay is necessary.

In preparing the ingredients comprising the dark burning mixture of the invention it has been found that most satisfactory results are obtained when the barium peroxide is of such a particle size as to pass through a U. S. standard sieve, mesh size 200/000, and the sulfide of such a particle size as to pass through a U. S. standard sieve, mesh size 325/000. A small percentage of lubricant or hinder may be added to a mixture of the foregoing substance and the ingredients then thoroughly mixed in any suitable manner.

As shown in Fig. 2, the dark burning non-flash mixture 1 is preferably loaded in pellet 3 form into the tracer cavity 2 of the projectile 5, and then the pellet 3 is pressed into abutting engagement with the tracer mixture 4. In loading the igniter mixture into the tracer cavity of a projectile, it has been found that the best results are obtained when the mixture, preferably in pellet form, is pressed into the cavity at a pressure of 10,000 to 40,000 p. s. i. The mixture may be readily pressed into pellets prior to the loading operation at a pressure sufficient to consolidate the mixture when a binder and lubricant is present as an ingredient of the composition in small percentage.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A delayed ignition projectile tracer comprising a dark burning non-flash ignition pellet for igniting the projectile tracer, said pellet comprising 90-30% barium peroxide, 10-70% of a sulfide selected from the group consisting of chromium monosulficle, chromium tetrasulfide, and selenium sulfide and up to 10% of lubricant.

2. The projectile tracer of claim 1, wherein said pellet comprises 90-30% barium peroxide, 10-70% chromium 10 monosulfide and up to 10% of lubricant.

No references cited. 

1. A DELAYED IGNITION PROJECTILE TRACER COMPRISING A DARK BURNING NO-FLASH IGNITION PELLET FOR IGNITING THE PROJECTILE TRACER, SAID PELLET COMPRISING 90-30% BARIUM 